RICHMOND, Va. (AP) — Herman Cain and Mitt Romney are tied at the top of the Republican presidential field while Texas Gov. Rick Perry has plunged sharply among GOP registered voters in a new statewide poll in Virginia.

The Quinnipiac University Poll released Tuesday shows Cain, the former CEO of Godfather's Pizza, and Romney, a former Massachusetts governor, each favored by 21 percent of Republicans surveyed.

Perry, meanwhile, fell from a clear lead at 25 percent in the same poll a month ago to 11 percent among the 345 Republicans interviewed by telephone Oct. 5-9. Cain surged from 6 percent in September. Romney was at 19 percent a month ago, trailing only Perry.

The margin of sampling error among the subset of Republicans or GOP-leaning voters in the overall survey is plus or minus 5.3 percentage points.

"Herman Cain is moving up the ladder at breakneck speed," said Peter A. Brown, assistant director of the Quinnipiac University Polling Institute. He said the GOP choice in Virginia remains unsettled. "Romney's support remains relatively stable while other candidates rise and fall around him."

Texas Congressman Ron Paul was fourth in the survey at 9 percent, Minnesota Rep. Michele Bachmann and Newt Gingrich had 7 percent each, former Pennsylvania Sen. Rick Santorum was at 2 percent and former Utah Gov. Jon Huntsman at 1 percent. One-fifth of the respondents either didn't know whom they would support or wouldn't say, and 1 percent said they would not vote.

In other results, Quinnipiac found President Barack Obama's disapproval remains high among the 1,495 registered voters Quinnipiac interviewed over a longer period, Oct. 3-9. Fifty-two percent did not like the president's job performance. In September, that number was 54 percent.

For the full overall sample, the margin of sampling error was plus or minus 2.6 percentage points.

In 2008, Obama became the first Democrat to carry Virginia in a presidential race in 44 years, and both parties are already battling fiercely over what they consider a critical 2012 swing state. Cain, Perry and Bachmann have both campaigned in the state during the past three weeks, and Obama plans stops in four Virginia cities during a two-state bus tour next week promoting his jobs legislation.

Quinnipiac also found that the two frontrunners for next year's U.S. Senate race — Democrat Tim Kaine and Republican George Allen — would be deadlocked in a hypothetical one-on-one race. Each has primary opponents, but the poll did not cover other candidates in the nomination contests.

The results between the two former Virginia governors have never varied by more than 1 percentage point since Quinnipiac's first Senate race poll in June.